An organic light-emitting diode (OLED) display is one of the hot topics in the research field of flat-panel displays at present. Compared with a liquid crystal display (LCD), the OLED display has the advantages of low energy consumption, low production cost, self-luminescence, wide view angle, fast response and so on. At present, the OLED display has begun to gradually replace the traditional LCD in the display fields, such as mobile phones, PDAs, digital cameras.
In the OLED display technology, the design of a pixel drive circuit is the core technique. The LCD is voltage driven, i.e., controlling transmittance and brightness of liquid crystal by using a stable voltage; and differing from the LCD, the OLED display is current driven, controlling an OLED device to emit light by using a stable current. In the traditional OLED displays, generally, the light emission of the OLED device is controlled by employing a 2T1C pixel circuit. As shown in FIG. 1, the 2T1C pixel circuit is composed of a driving thin film transistor (TFT) T2, a switching thin film transistor T1 and a storage capacitor (Cs for short), the T1 is connected to a scan line, and also connected to a data line; when the scan line selects a row, a voltage Vscan of the scan line is at a low level, the T1 is turned on, and a voltage Vdata of the data line is written into the Cs through the T1; when the scan in this row is finished, the Vscan is changed to a high level, the T1 is cut off, and the voltage stored on the Cs drives the T2 to generate a current for driving the OLED, thereby ensuring that the OLED continuously emits light in one frame time; a saturation current, i.e., the current flowing through the OLED, of the T2 is IOLED=K(VGS−Vth)2, where VGS is a gate-source voltage of the T2, and Vth is a threshold voltage of the T2. It can be seen that IOLED is related to the threshold voltage Vth of the T2. Moreover, due to the reasons of manufacturing process and aging of devices, the threshold voltages Vth of the driving TFTs in respective pixels may drift, i.e., the threshold voltages of the driving TFTs in respective pixels are inconsistent, easily resulting in different currents for the OLED flowing through the respective pixels due to the different threshold voltages of the driving TFTs thereof, so that a display brightness of a display screen is non-uniform, thereby affecting a display effect of the whole image.
In order to further eliminate the impact of the threshold voltage of the driving TFT on the drive current, a pixel circuit including more TFTs and Css has emerged, which includes a compensation circuit configured to compensate the threshold voltage of the driving TFT. However, in the prior art, one pixel circuit is only limited in one sub-pixel unit. FIG. 2 shows an arrangement mode of the sub-pixel units in the prior art, each sub-pixel unit has one pixel circuit, and each pixel circuit includes an exclusive compensation circuit, so that the sub-pixel units are all connected to the data lines. In the case of meeting the driving requirements, considering many factors such as distribution space of the TFT, the Cs and the data line, the pixel circuit in the prior art makes it difficult to achieve a finer pixel resolution by compressing the pixel pitches.
Meanwhile, in the touch field at present, two modes, which are capacitive touch and photosensitive touch, are the most easily accepted and recognized by consumers, if the above two touch technologies can be integrated to the OLED display to achieve integration of the manufacture procedure of the touch and that of the OLED display together, the integration representing a high added value and the latest technical functions are hound to occupy an impregnable position in the field of display technology in the future. However, the addition of the above two touch functions is bound to further increase the pixel pitch, which makes it more difficult to achieve a fine pixel resolution.